Polyester Resin vs. Epoxy Resin — What’s the Difference?

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As someone who’s spent a fair bit of time in the workshop, I’ve gotten pretty familiar with both polyester resin and epoxy resin. They’re staples in crafting, construction, and manufacturing, and for good reason. Each one brings its own set of characteristics to the table, tailored for various projects.

Let me walk you through the main differences between these resins. My goal is to give you the insights you need to pick the one that’s just right for your particular project.

What is Polyester Resin?

Polyester resin is a type of synthetic resin made through a chemical reaction between a type of polyester and a hardening catalyst. 

It is often used in various applications such as fiberglass-reinforced plastics, laminates, coatings, and casting. 

What Are the Advantages of Using Polyester Resin?

In my experience, I’ve seen polyester resin become a go-to material in many fields. It has a set of distinct advantages that really stand out, which explains why it’s so prevalent across different industries and applications.

Castin Craft Clear Polyester Casting Resin


One of the primary benefits of polyester resin is its affordability. Compared to other types of resins like epoxy, polyester resin is more budget-friendly. 

This cost-effectiveness is particularly advantageous for large-scale projects where a significant amount of resin is required.

Quick Curing Time

Polyester resin has a relatively fast curing time, meaning it solidifies and hardens relatively quickly after application. This rapid curing is beneficial when time-sensitive resin projects need to be completed promptly. 

It allows for efficient production and shorter waiting periods, increasing overall productivity.

Versatility in Applications

Polyester resin is incredibly versatile. I’ve used it for everything from fiberglass-reinforced products and laminates to making some pretty neat decorative pieces. It’s one of those materials that can really cover a broad spectrum of applications.

curing polyester resin

Its adaptability stems from its compatibility with various materials and its ability to provide a smooth and glossy finish, enhancing the aesthetic appeal of the final product.

Good Weather Resistance

Polyester resin exhibits reasonable weather resistance, making it suitable for outdoor applications. 

It can withstand exposure to UV rays and general environmental conditions without significant degradation, maintaining its integrity over time.

Low Shrinkage

When curing, polyester resin experiences minimal shrinkage. This characteristic ensures that the final product retains its intended dimensions and shape accurately. 

polyester craft

I’ve found that low shrinkage is key for projects where precision really matters. It’s essential when you’re working on something that requires exact measurements and fine detail.

Easy Availability

Polyester resin is widely available in the market, making it convenient to source for various projects. 

Its popularity and accessibility also translate to an extensive range of additives, pigments, and accessories specifically designed to enhance its properties and performance.

What is Epoxy Resin?

Epoxy resin is a versatile and durable synthetic compound created by mixing epoxy resin and a hardening agent. It’s valued for its exceptional bonding strength, chemical resistance, and low shrinkage during curing. 

pouring epoxy

I’ve relied on epoxy resin time and again for its strength and durability, especially when I’m working on coatings, adhesives, composites, or even some of my art projects. It’s the ability of this resin to form robust, enduring bonds and that signature glossy finish that really makes it invaluable in my work.

What Are the Advantages of Using Epoxy Resin?

Epoxy resin offers a plethora of advantages, making it a favored option across industries and creative endeavors.

Exceptional Bonding Strength

One of the standout features of epoxy resin is its remarkable bonding strength. 

It forms incredibly strong adhesive bonds with various materials, ensuring structural integrity and durability in applications like construction, woodworking, and composite manufacturing.

High Chemical and Solvent Resistance

Epoxy resin exhibits superior resistance to chemicals, acids, and solvents. This attribute makes it an ideal choice for environments where exposure to corrosive substances is likely. 

dyeing epoxy resin

It’s commonly used in laboratory settings, industrial coatings, and chemical storage facilities.

Versatility in Formulation

Epoxy resin’s formulation can be tailored to specific project requirements. 

It can be modified with various additives, fillers, and reinforcements to achieve desired properties such as increased flexibility, enhanced UV resistance, or improved thermal conductivity.

Low Shrinkage and Minimal VOCs

During the curing process, epoxy resin experiences minimal shrinkage, ensuring that the final product maintains its intended dimensions accurately. 

Additionally, epoxy resins generally have lower levels of volatile organic compounds (VOCs) [1], contributing to better indoor air quality and reduced environmental impact.

Aesthetic Appeal and Finishing

Epoxy resin is renowned for its ability to create a glossy, glass-like finish on surfaces. This aesthetic quality enhances the visual appeal of products, making them a popular choice for artistic applications, jewelry making, and tabletops. But can you utilize food colorings in resin? Find out more. 

epoxy resin home decor

Durability and Longevity

The inherent strength of epoxy resin translates to exceptional durability and longevity. Epoxy-coated surfaces can withstand wear and tear, making them suitable for high-traffic areas, industrial flooring, 3D epoxy floorings, and marine applications.

High Electrical and Thermal Insulation

Epoxy resin boasts excellent electrical insulation properties, making it indispensable in electronics, electrical components, and insulation systems. 

Furthermore, it exhibits respectable thermal insulation properties, lending itself to applications requiring heat resistance.

How Does Polyester Resin Compare to Epoxy Resin?

When considering the choice between polyester resin and epoxy resin, understanding their differences is crucial in determining the best fit for your project. Let’s explore how these two resins compare in various aspects.

Chemical Composition and Curing Process

I’ve mixed polyester resin with a hardening catalyst to initiate its curing process. This process, known as polymerization, is fascinating because it’s not just about the resin hardening, it’s a chemical reaction that actually generates heat. Watching this reaction take place is a clear reminder of the intricate science behind even the simplest of materials I use.

curing epoxy resin

On the other hand, epoxy resin is created by mixing epoxy resin with a hardening agent. 

It is cured through a process called cross-linking, where the molecules chemically bond to each other. This fundamental difference in curing mechanisms influences their properties and performance.

Strength and Bonding

Epoxy resin stands out with its exceptional bonding strength. It forms robust and durable bonds with a wide range of materials, making it a preferred choice in applications where structural integrity is vital. 

Polyester resin, while offering decent bonding strength, doesn’t match the superior adhesion capabilities of epoxy. This factor often drives the selection between the two based on the specific demands of the project.

Mechanical Properties

Epoxy resin exhibits better mechanical properties such as tensile strength, impact resistance, and flexibility. Its ability to withstand stress and strain without fracturing makes it suitable for load-bearing applications. 

polish epoxy resin mirror finish

Polyester resin generally holds up well under typical conditions. However, when it’s put under extreme mechanical stress, I’ve noticed it doesn’t always perform quite as robustly as one might hope.

Chemical and Environmental Resistance

Epoxy resin surpasses polyester resin in terms of chemical resistance. Epoxy’s resistance to acids, solvents, and harsh chemicals makes it suitable for industrial and laboratory settings. 

Polyester resin is generally more susceptible to chemical degradation. Additionally, epoxy resin demonstrates better resistance to environmental factors like UV radiation, ensuring its stability over prolonged outdoor exposure.

Cost and Availability

Polyester resin holds an advantage in terms of cost-effectiveness. It is often more budget-friendly than epoxy resin, making it a preferred choice for larger projects or applications where budget constraints play a significant role. Moreover, polyester resin is widely available, contributing to its popularity.

Aesthetic Considerations

Epoxy resin’s ability to create a high-gloss, clear finish contributes to its appeal in artistic and decorative applications. Its aesthetic quality enhances the visual appeal of products like jewelry, artwork, and furniture. 

table with Upstart Epoxy Deep Pour Epoxy Resin Kit DIY

I’ve finished plenty of projects with polyester resin and have always appreciated the smooth finish it provides. But when it comes to achieving that deep, crystal-clear look, epoxy resin is in a league of its own—it’s simply unmatched.


In the choice between polyester resin and epoxy resin, consider your project’s needs. Epoxy offers strong bonds, chemical resistance, and versatility, but at a higher cost. 

Polyester is budget-friendly, cures quickly, and suits less demanding tasks. Choose based on performance, budget, and intended use.

Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You've probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
Robert Johnson

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